The present invention relates in general to regulation of mass streams of finely divided and fine-grained solid fuel which are pneumatically conveyed at an arbitrary concentration of solid particles and at an arbitrary pressure to gasifying reactors or to burners of heaters and steam boilers.
Known technical solutions for the regulation of mass streams of the aforedescribed type comprise generally the following process steps:
withdrawing or discharging the pulverized solid material from a storage bin or dosing vessel with or without a fluidizing bed, by regulating pressure or by means of throttling devices; PA1 diluting the dosed solid material to a minute concentration of solid particles (less than 10 kg/m.sup.3) so as to make the evaluation of the mass stream by measurement possible. PA1 Due to the absence of reliable measuring methods for two-phase streams having an arbitrary concentration of solid particles, and due to the absence of knowledge technologically unambiguous controllability of the density of the mass stream to be dosed, excessively complicated regulating processes were necessary, and the determination of the mass stream rate took place in the region of maximum rarification (German Pat. Nos. 2,554,565 and 2,902,911). PA1 p is the pressure in the dosing container; PA1 V.sub.G is the measured value of the fluidizing gas stream related to an operational condition; PA1 V.sub.G(N) is the measured amount of fluidizing gas related to the normal condition; PA1 .rho..sub.S is the loose or bulk density value of the finely divided fuel particles in the dosing container; PA1 .rho..sub.K is the grain density of the dusty solid fuel; PA1 .rho..sub.G is the gas density in the operational condition; and m.sub.K is the mass stream rate. PA1 V.sub.KG is the amount of compensation gas related to an operational condition.
From the DD Pat. No. 147,188 a regulating method of a mass stream by means of a fluidizing gas in the dosing container is described. This known method, however, has the disadvantage that, particularly in the case of strong weight rate of flow, an excessive mutual influence between the density and the mass stream takes place.
Another known method according to DD Pat. No. 147,933 uses regulating throttles before the intake of the mass stream of solid particles into the supply pipe. This known method, however, has a relatively small regulating range, and in the case of high concentrations of the solid material and at low weight rate of flow, the mass stream due to shock effects may undergo retardation or non-uniformity of its flow.